Methinks they're being overly cautious. I upgraded my home Yoga Pro, my tablet Yoga and my work Carbon X1 without uninstalling anything & didn't bump into problems. It is interesting, as Daniel mentioned, that they're recommending you uninstall all the Lenovo software. It's not like they weren't aware this was coming or didn't have sufficient time to plan for Win10. That is odd.

Those are all programs that come preinstalled on Lenovo PCs. And the way I see it "Applications that are recommended to be uninstalled before upgrading" should actually read: We couldn't care to test all our bloatware for Windows 10, so you better uninstall it - most people do so anyway.

My old ThinkPad T410 runs Windows 10 just fine, but according to Lenovo running Windows 10 on that machine is "not supported". Which actually reads as: We don't care if it's running Windows 10, it's out of warranty - if you run into problems don't call us.